The Neuron презентация

Parts of the neuron

Dendrites
The dendrites are the part of the neuron that receive signals from other neurons.
The dendrites of a single neuron are collectively called a dendritic tree

Dendrites
The dendrites are covered with specialized structures
called dendritic spines that receive some types of synaptic input

Axon
The axon is the part of the neuron that transmits the signal to another neuron.
The axon begins with a region called the axon hillock
Axons may extend from less than a millimeter to over a meter long

Axon
The end of axon is called the axon terminal
The terminal is a site where the axon comes in contact with other neurons and passes information on to them.
Axon usually is covered by myelin sheath

The cell body
The cell body is a part of neuron that contains the nucleus and various organelles
The cell body is the metabolic and trophic center of the neuron.

Classification of neurons
1. Classification Based on the Number of Neurites
Unipolar
Bipolar
Multipolar

Classification of neurons
2. Classification Based on Axon Length
projection neurons (pyramidal cells)
local circuit neurons (stellate cells in the cortex)

Classification of neurons
3. Classification Based on Body Shape
pyramidal
Multangular
circular
oval

Classification of neurons
4. Classification Based on Functions
afferent (sensory)
efferent (motor)
associative

Synapses
Synapse the specialized junction where one part of a neuron contacts and communicates with another neuron or cell type (such as a muscle or glandular cell).

Classification of Synapses
1. The place of junction
neuromuscular junction
neuro-neural junction
neuro-glandular junction

Classification of Synapses
2. Synaptic arrangements in the CNS
axodendritic synapse
axosomatic synapse
axoaxonic synapse

Classification of Synapses
3. Based of type of influence
excitatory
inhibitory

Classification of Synapses
3. Based on type of synaptic transmission
electrical synapses
chemical synapses

Electrical synapses
Six connexins combine to form a channel called a connexon
Two connexons (one from each cell) combine to form a gap junction channel

Chemical synapses
Axon terminal
Presynaptic membrane
Postsynaptic membrane
Synaptic cleft
Synaptic vesicles
Postsynaptic receptors

Nerve fibers

Classification of nerve fibers
unmyelinated fibers
myelinated fibers

Myelin sheath
Myelin sheath is a fatty white substance that surrounds the axon of nerve fibers, forming an electrically insulating layer
The production of the myelin sheath is called myelination

Nodes of Ranvier
Nodes of Ranvier are periodic gaps in the insulating myelin sheaths of myelinated axons where the axonal membrane is exposed to the extracellular space
Nerve conduction in myelinated axons is referred to as saltatory conduction.

Glial cells
Glial cells (neuroglia or glia) are non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems

Classification of glial cells
Schwann cells supply the myelin for the peripheral nervous system
Oligodendrocytes myelinate the axons of the central nervous system.
Astrocytes